It has three protruding horizontal blades, most likely designed to separate the planks of the opposing ship before breaking them individually with the vertical front edge of the ram. Separating planks before breaking them would have softened the collision for the attacking ship somewhat, and would have made it less likely for the ram to be wedged in the broken ship. The way the blades are spread (the top upward an the bottom downward) would have probably inflicted more splintering the planks as the ram retreated after the blow.
Exhibited at the Archaeological Museum of Piraeus, Greece.